Are you a UNIX guru?

[mailin 0]

Then please help me!

I missed class last week - and the book (Teach yerself UNIX in 24 hours ) is confusing me.

I have 1 more question on my homework assignment but I have to study for the test tonight too and I'm feeling very overwhelmed.

Create a shell script that will copy a file (named myls) to a backup directory located in your home directory.

I feel so stupid that I can't figure this out

Thanks for any and all help!

Jen

Arianna Frances

[kaerock 1]

mkdir ~/backup
cp myls ~/backup


That'll be $2, please.

You be the king and I'll overthrow your government. --KRS-ONE

[AggieDave 6]

Quote

mkdir ~/backup
cp myls ~/backup


That'll be $2, please.

For a Unix guy, that's more like $40.

--"When I die, may I be surrounded by scattered chrome and burning gasoline."

[kaerock 1]

skydiver rate :>

You be the king and I'll overthrow your government. --KRS-ONE

[mailin 0]

but is that a script? the example my teacher gave in notes (as bare minimum as they are) have something a bit different

if it was just a matter of creating the directory and copying the file... well crap, thats the easy part

EDIT TO ADD MY TEACHERS EXAMPLE:

Example:

mycopy letter memo

The above would copy the files letter and memo to /home/rdefe/backup


Jen

Arianna Frances

[CrazyIvan 0]

Quote

Quote

mkdir ~/backup
cp myls ~/backup


That'll be $2, please.

For a Unix guy, that's more like $40.

In the I.T field nowadays, $2 is being OVERPAID , a guy in India can do the same for 25 cents

__________________________________________
Blue Skies and May the Force be with you.

[indyz 1]

Quote

Quote

mkdir ~/backup
cp myls ~/backup


That'll be $2, please.

For a Unix guy, that's more like $40.

I was gonna say $175/hr minimum two hours.

Make sure you put the proper shebang at the top of the file ("#!/bin/sh" or whatever).

[indyz 1]

Ok, try this:

#!/bin/bash


mkdir -p /home/rdefe/backup

cp $* /home/rdefe/backup

call the script mycopy and do a "chmod +x" on it.

[kaerock 1]

Actually, that example is terribly wrong.

If you look at the manpage for 'cp', you'd see that the last argument in the argument list would be the destination. That example would copy 'letter' to 'memo', assuming 'mycopy' worked like 'cp'.

To make what I posted a script, you put the text in a file, then run 'chmod 700 ' and you run the file. "#!/bin/sh" is probably not required in this case, although it is good pratice to include it at the beginning of the file.

-R

Quote

but is that a script? the example my teacher gave in notes (as bare minimum as they are) have something a bit different

if it was just a matter of creating the directory and copying the file... well crap, thats the easy part

EDIT TO ADD MY TEACHERS EXAMPLE:

Example:

mycopy letter memo

The above would copy the files letter and memo to /home/rdefe/backup


Jen

You be the king and I'll overthrow your government. --KRS-ONE

[kaerock 1]

This assumes bash is on the machine and also located in the ''/bin" directory, this is not portable. Hard-coding the location of the home directory is also dangerous, using "~" or "${HOME}" is preferred as it is portable.

-R

Quote

Ok, try this:

#!/bin/bash


mkdir -p /home/rdefe/backup

cp $* /home/rdefe/backup

call the script mycopy and do a "chmod +x" on it.

You be the king and I'll overthrow your government. --KRS-ONE

[indyz 1]

Quote

This assumes bash is on the machine and also located in the ''/bin" directory, this is not portable. Hard-coding the location of the home directory is also dangerous, using "~" or "${HOME}" is preferred as it is portable.

She specified the directory. And I was trying to keep things simple and my assumptions about bash will be correct on 95% of modern unix machines.

[flyingferret 0]

If I remember anything about school, the example is probably 'wrong' for those of us in the working world. However, pointing that out never makes the teacher very happy.

--
All the flaming and trolls of wreck dot with a pretty GUI.

[mailin 0]

Yes, i using bash....

but I'm still horribly confused...

I hate this book.... I was able to copy the file to the newly created backup directory... but I did it using the cp command

should I be using an alias to rename the cp command according to the example that he used?

Jen

Arianna Frances

[AggieDave 6]

Quote

However, pointing that out never makes the teacher very happy

Most computer science types are teachers because they weren't good enough to make it as a real IT type...or they just weren't good enough programmers, and there's a rare, very rare type that got tired of working the real world and decided to teach.

So basically a lot of the teachers don't know fuckall beyond what the book says and what they want to see from their students. They don't know real world application.

--"When I die, may I be surrounded by scattered chrome and burning gasoline."

[mailin 0]

Unfortunately, this is not the case with mine... (wish it was)

He works as a unix system admin for Fleet Bank (now Bank of America) during the day and teaches this class one night a week (just as he has for 9 years now).

Sometimes I think he takes for granted that we're STUDENTS who don't know jack sh!t about this. I really hope my first job doesn't involve UNIX....

Jen

Arianna Frances

[AggieDave 6]

Quote

Unfortunately, this is not the case with mine... (wish it was)

He works as a unix system admin for Fleet Bank (now Bank of America) during the day and teaches this class one night a week (just as he has for 9 years now).

Sometimes I think he takes for granted that we're STUDENTS who don't know jack sh!t about this. I really hope my first job doesn't involve UNIX....

You're VERY VERY lucky. Use that guy's knowledge and experience and learn as much as you can from it. That'll help you out a lot in the long run.

Oh, and you should be motivated to learn UNIX, it kicks the shit out of everything that MS ever tried to make.

--"When I die, may I be surrounded by scattered chrome and burning gasoline."

[kaerock 1]

I'm guessing he wanted you to figure that you need to use 'cp'. That's the command for the job, I can't see why he'd want to obfusicate it (any more than it already is) by making you alias common commands.

-R

Quote

Yes, i using bash....

but I'm still horribly confused...

I hate this book.... I was able to copy the file to the newly created backup directory... but I did it using the cp command

should I be using an alias to rename the cp command according to the example that he used?

Jen

You be the king and I'll overthrow your government. --KRS-ONE

[indyz 1]

Quote

should I be using an alias to rename the cp command according to the example that he used?

That's another way to do it.

alias mycopy="cp $* ~/backup"

[flyingferret 0]

Agreed, with Dave, you are very lucky, i only had a few profs like that.
Your first job might not include unix, because some sysadmin is writing scripts to do it
You wanna impress him, use this. All nicely commented and everything. It will impress him. BUT you better be able to explain it if he asks. On the other hand you could just use the core stuff and chunk the rest.

Quote

A Simple Backup Script

This script demonstrates a number of common ways to use Bash. A slick Bash trick is to take a script like this, and execute it one line at a time. That's a great way to build and test a script.

To run it as a script, save it as text file, with a nice name like "backup," and make it executable:

$ chmod +x backup

There are severals ways to run it. Change to the directory it's in, and use one of these:

$ ./backup
$ bash backup

Or, do what leet geeks do, and put it in /usr/bin. Or keep it all to yourself- create your own personal scripts directory, and put it in your path:

$ mkdir ~/scripts

Append to your PATH, using your own filepath, of course.

/home/carla/scripts

This allows you to run the script like any other command:

$ backup

And now, the script itself:

#!/bin/bash
## This is the famous "sha-bang" statement,
## that tells the shell which command
## interpreter to use. See man magic
## to learn the inner workings of sha-bang.
## this script uses the tar, mkdir, and cp commands
## plus Bash's conditional statements
## smart admins write lots of comments

# test for existing backup directory
# if it does not exist, create it
# -e is the Bash way of asking "does this file exist"
# $ means variable substitution. HOME is a builtin
# Bash variable.
if [ -e $HOME/1backups ]
then
echo "The backup directory exists."
else
echo "A backup directory does not exist, and will be created."
mkdir $HOME/1backups
echo "A backup directory has been created"
fi

# now we define our own variables
# location of files to backup
FILES=$HOME/archive-files
# name of compressed archive
ARCHIVENAME=backups.tgz
# location of backup directory
BACKUPDIR=/archive/carla/
# create compressed archive, copy to backup directory
tar czf $ARCHIVENAME $FILES
cp -ap $ARCHIVENAME $BACKUPDIR

if [ -e $BACKUPDIR/$ARCHIVENAME ]
then
echo "Jolly good show, the backup worked!"
else
echo "Dagnabit, the backup failed. Time to debug."
fi

Going through this script and understanding which parts are Bash commands, and which are Linux commands, is important for understanding how to put scripts together.

--
All the flaming and trolls of wreck dot with a pretty GUI.

[Kris 0]

My name is Inigo Montoya, you Kill -9 my process, prepare to Vi.

The script posted right above this post is the bomb-diggity.

Sky, Muff Bro, Rodriguez Bro, and
Bastion of Purity and Innocence!™

[mailin 0]

Thanks for all your help guys. I realize I should probably feel more fortunate with this class... but what I feel is overwhelmed.

This was a UNIX Admin course that was crammed into 5 weeks - its a 3 part course that will next include programming for UNIX (which I thankfully don't have to take). As a programming major I should be enjoying it, but I'm feeling confused.... I'll eventually get it, just not in this class.

The error I'm getting when creating the alias is such:

$ cd

$ ls

backup  big.ouput  big.output  buckaroo  demo  myls  project  whoison

$ cd /home

$ ls

aevan  gclar  nfakh  os18  os27  os36  os45  os54  os63  os72  os9

aferr  gwolc  os1    os19  os28  os37  os46  os55  os64  os73  pjean

balbr  hmuhl  os10   os2   os29  os38  os47  os56  os65  os74  psoum

bgrah  jdece  os11   os20  os3   os39  os48  os57  os66  os75  rdefe

cmarq  jogid  os12   os21  os30  os4   os49  os58  os67  os76  rfont

cmore  jvinc  os13   os22  os31  os40  os5   os59  os68  os77  rguin

dkrus  kchho  os14   os23  os32  os41  os50  os6   os69  os78  style

donp   ljack  os15   os24  os33  os42  os51  os60  os7   os79  svinc

egonz  mflah  os16   os25  os34  os43  os52  os61  os70  os8   wpass

ffont  nbroo  os17   os26  os35  os44  os53  os62  os71  os80  wprice

$ cd /home/jdece

$ ls

backup  big.ouput  big.output  buckaroo  demo  myls  project  whoison

$ unalias mycopy

$ alias mycopy="cp $* /backup"

$ mycopy demo

cp: cannot stat `/backup': No such file or directory

$ ls

backup  big.ouput  big.output  buckaroo  demo  myls  project  whoison

$ unalias mycopy

$ ls -l

total 28

drwxrwxr-x    2 jdece    jdece        4096 Oct  5 14:20 backup

-rw-rw-r--    1 jdece    jdece          31 Oct  5 11:48 big.ouput

-rw-rw-r--    1 jdece    jdece         251 Oct  5 10:58 big.output

-rw-rw-r--    1 jdece    jdece         279 Oct  5 11:56 buckaroo

-rw-rw-r--    1 jdece    jdece         198 Oct  5 10:55 demo

-rw-rw-r--    1 jdece    jdece           0 Oct  5 13:07 myls

drwxrwxr-x    6 jdece    jdece        4096 Sep 28 15:05 project

-rw-rw-r--    1 jdece    jdece         185 Sep 28 14:44 whoison

$ ls -f

.             .bash_profile  .bash_history  .viminfo    myls       backup

..            .bashrc        project        demo        buckaroo

.bash_logout  .emacs         whoison        big.output  big.ouput

$ ls -F

backup/  big.ouput  big.output  buckaroo  demo  myls  project/  whoison

$ alias mycopy="cp $* backup"

$ mycopy demo

cp: omitting directory `backup'

$

What am I doing wrong that alias is not working?

Arianna Frances

[mailin 0]

I know it will work, and do it well....

but we haven't gone over if/then/else statements in this class yet


How come when your learning something they show you the way you SHOULDN"T do something before they show you the way you should, or the way that is best?

Jen

Arianna Frances

[indyz 1]

you want ~/backup (which expands automagically to /home/youusername/backup), not /backup (which is the directory backup in the root of the filesystem, which you don't have write access to)

[mailin 0]

makes sense - thanks!

$ alias mycopy="cp $* ~/backup"

$ ls

myls

$ cd /home/jdece

$ ls

backup  big.ouput  big.output  buckaroo  demo  myls  project  whoison

$ mycopy demo

cp: omitting directory `/home/jdece/backup'

Still getting that stupid error tho

Arianna Frances

[flyingferret 0]

Do you have to alias?
Or just call the script?

--
All the flaming and trolls of wreck dot with a pretty GUI.